Watford's Nigerian striker Isaac Success is in line to make his first English Premier League start when his club face Middlesbrough at the Riverside on Sunday.

The 20-year-old who made five substitute appearances for Walter Mazzarri's side since joining the club this summer missed a chance to make his debut for the senior national team in last Sunday's World Cup qualifier against Zambia in Ndola due to a leg injury.

Success has since rejoined his teammates in training but his Watford manager Mazzarri thinks the former Granada star may not be capable of completing 90 minutes at the Riverside if he does get the nod to start.

"Success has recovered very well and looks OK," Mazzarri said during his pre-match press conference on Friday.

"The only thing I need to check is if he has the 90 minutes in him and if he has recovered completely from his injury.

"I’m reflecting on him and reflecting on all the options. I am evaluating all the players during the week."

Mazzarri then tasked Success to further improve his defensive abilities.

"I think he’s adapting very well to English football," Mazzarri added "Every time he comes on, including at Burnley where the team played badly, he was one of the best.

"I need to know if he’s got 90 minutes in him after his injuries."

Mazzarri also denied media reports that Success fabricated his injury to avoid paying his air fare to travel to Nigeria.

"We have a very good relationship with the national team," Mazzarri said. "The proof is that immediately after the game we sent the e-mail to the Nigerian federation and spoke with them on the phone confirming he had an injury.